1. Field of the Invention
This invention relates to the treatment of non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH).
2. Description of the Related Art
NAFLD and NASH
Non-alcoholic fatty liver disease (NAFLD) is a disorder affecting as many as 1 in 3-5 adults and 1 in 10 children in the United States, and refers to conditions where there is an accumulation of excess fat in the liver of people who drink little or no alcohol. The most common form of NAFLD is a non-serious condition called hepatic steatosis (fatty liver), in which fat accumulates in the liver cells: although this is not normal, by itself it probably does not damage the liver. NAFLD most often presents itself in individuals with a constellation of risk factors called the metabolic syndrome, which is characterized by elevated fasting plasma glucose (FPG) with or without intolerance to post-prandial glucose, being overweight or obese, high blood lipids such as cholesterol and triglycerides (TGs) and low high-density lipoprotein cholesterol (HDL-C) levels, and high blood pressure; but not all patients have all the manifestations of the metabolic syndrome. Obesity is thought to be the most common cause of NAFLD; and some experts estimate that about two-thirds of obese adults and one-half of obese children may have fatty liver. The majority of individuals with NAFLD have no symptoms and a normal physical examination (although the liver may be slightly enlarged); children may exhibit symptoms such as abdominal pain and fatigue, and may show patchy dark skin discoloration (acanthosis nigricans). The diagnosis of NAFLD is usually first suspected in an overweight or obese person who is found to have mild elevations in their liver blood tests during routine testing, though NAFLD can be present with normal liver blood tests, or incidentally detected on imaging investigations such as abdominal ultrasound or CT scan. It is confirmed by imaging studies, most commonly a liver ultrasound or magnetic resonance imaging (MRI), and exclusion of other causes.
Some people with NAFLD may develop a more serious condition called non-alcoholic steatohepatitis (NASH): about 2-5% of adult Americans and up to 20% of those who are obese may suffer from NASH. In NASH, fat accumulation in the liver is associated with inflammation and different degrees of scarring. NASH is a potentially serious condition that carries a substantial risk of progression to end-stage liver disease, cirrhosis and hepatocellular carcinoma. Some patients who develop cirrhosis are at risk of liver failure and may eventually require a liver transplant.
NAFLD may be differentiated from NASH by the NAFLD Activity Score (NAS), the sum of the histopathology scores of a liver biopsy for steatosis (0 to 3), lobular inflammation (0 to 2), and hepatocellular ballooning (0 to 2). A NAS of <3 corresponds to NAFLD, 3-4 corresponds to borderline NASH, and ≧5 corresponds to NASH. The biopsy is also scored for fibrosis (0 to 4).
NASH is a leading cause of end-stage liver disease; while NAFLD, and to an even greater degree NASH, are intimately related to states of the metabolic syndrome, including insulin resistance (pre-diabetes) and type 2 diabetes mellitus (T2DM), and abdominal obesity. T2DM has been the most prominent predictor for a poor prognosis in NAFLD, whereas elevated liver enzymes are considered unreliable. NASH develops much more frequently in the presence of longstanding T2DM, and the majority of patients with cryptogenic cirrhosis are obese and/or diabetic. Studies have demonstrated that 60% of patients with T2DM and NAFLD had biopsy-proven NASH, and that advanced hepatic fibrosis was present in 75% of those with diabetes and hypertension compared to only 7% without either condition. Haukeland, “Abnormal glucose tolerance is a predictor of nonalcoholic steatohepatitis and fibrosis in patients with non-alcoholic fatty liver disease”, Scand J. Gastroenterol., 40, 1469-1477 (2005), reported that impaired glucose tolerance (IGT) and T2DM were the only independent risk factors for severe NAFLD and NASH, increasing the odds ratio almost 4-fold. Mofrad, “Clinical and histological spectrum of nonalcoholic fatty liver disease associated with normal ALT levels”, Hepatology, 37, 1286-1292 (2003), reported a study that demonstrated the lack of predictive value for elevated liver transaminases to diagnose NASH in patients with NAFLD and found T2DM to be the only factor independently associated with an increased risk of advanced fibrosis. Thus, NASH is an overlooked complication of T2DM that is frequently associated with fibrosis and in approximately 10% of patients results in cirrhosis; while the risk of hepatocellular carcinoma is also increased in patients with T2DM and NASH. Patients with NAFLD and NASH usually demonstrate mixed dyslipidemia and the other metabolic derangements described above, including an atherogenic low-density lipoprotein (LDL) phenotype consisting of predominantly of small dense particles. Both metabolic syndrome and NAFLD/NASH are characterized by increased cardiovascular inflammation as measured by elevations in high sensitivity C-reactive protein (hsCRP) and other inflammatory cytokines.
There is significant worldwide incidence of obesity, metabolic syndrome, pre-diabetes and diabetes, with the prevalence of diabetes worldwide predicted to double to 366 million by 2030. The US population with diabetes has been estimated at 25.4 million (11.5% prevalence) in 2011 and 37.7 million (14.5%) by 2031, with 20.2% of Hispanic adults having diabetes. Because approximately 70% of persons with T2DM have a fatty liver, and the disease follows a more aggressive course with necroinflammation and fibrosis (i.e., NASH) in diabetes, the epidemiology of diabetes suggests significant increases in NASH and chronic liver disease. Using MRI for the noninvasive assessment of hepatic steatosis, the prevalence of NAFLD, when defined as liver fat >5%, has been estimated to be 34% in the USA or approximately 80 million people, and as many as two out of three obese subjects. However, this prevalence is believed to be much higher in T2DM. In a series of 107 unselected patients with T2DM, the prevalence of NAFLD by MRI was 76%, which is similar to recent studies from Italy and Brazil. Recent studies have indicated that the prevalence of NAFLD is rapidly rising in obese children and adolescents, especially those of Hispanic ancestry.
Treatments for NAFLD and NASH
There are no drugs currently approved to prevent or treat NAFLD or NASH. A number of pharmacological interventions have been tried in NAFLD/NASH but with overall limited benefit. Antioxidant agents may arrest lipid peroxidation and cytoprotective agents stabilize phospholipid membranes, but agents tried unsuccessfully or with only modest benefit so far include ursodeoxycholic acid, vitamins E (α-tocopherol) and C, and pentoxifylline, among others. Weight-loss agents such as orlistat have had no significant benefit compared to just the use of diet and exercise to achieve weight loss (“weight loss alone”). Most weight-loss studies in NAFLD/NASH have been pilot studies of short duration and limited success, reporting only a modest improvement in necroinflammation or fibrosis. A randomized, double-blind, placebo-controlled 6-month trial (Belfort, “A placebo-controlled trial of pioglitazone in subjects with nonalcoholic steatohepatitis”, N. Engl. J. Med., 355, 2297-2307 (2006)) of weight loss alone against pioglitazone, a thiazolidinedione peroxisome proliferator-activated receptor-γ (PPARγ) agonist and insulin sensitizer, failed to demonstrate any improvement for weight loss alone, but treatment with pioglitazone improved glycemic control, insulin sensitivity, indicators of systemic inflammation (including hsCRP, tumor necrosis factor-α, and transforming growth factor-β), and liver histology in patients with NASH and IGT or T2DM. Treatment with pioglitazone also ameliorated adipose, hepatic, and muscle IR, and was associated with an approximately 50% decrease in necroinflammation (p<0.002) and a 37% reduction in fibrosis (p=0.08). Improvement in hepatocellular injury and fibrosis has been recently reported in another controlled trial with pioglitazone of 12 months duration. In contrast, while the first randomized clinical study with rosiglitazone, the other thiazolidinedione approved for diabetes treatment, in NASH demonstrated a reduction in IR, plasma alanine aminotransferase (ALT) levels and steatosis, rosiglitazone treatment had no significant effect on necrosis, inflammation, or fibrosis. A preliminary report of the 2-year, open-label follow-up of this trial was also disappointing, with no significant benefit from rosiglitazone treatment. Thus, the pharmacological agent with the most robust efficacy in NASH is pioglitazone. Unfortunately, pioglitazone is also associated with a significantly increased risk of weight gain, edema, congestive heart failure, and osteoporotic fractures in both women and men.
GW510516, a potent peroxisome proliferator-activated receptor-δ (PPARδ) agonist, ameliorated diet-induced obesity and insulin resistance in normal mice, an effect accompanied by enhanced metabolic rate and fatty acid β-oxidation. It also markedly improved diabetes as evidenced by substantial reductions in both glucose and insulin levels in genetically obese ob/ob mice. GW510516 has been shown in two Phase 1 studies in healthy subjects to reduce TGs, low-density-lipoprotein cholesterol (LDL-C), apolipoprotein B (apoB), and insulin levels, and improve HDL-C and insulin sensitivity, with one of the studies also showing a 20% reduction in hepatic fat; while a later study confirmed these effects in dyslipidemic subjects with abdominal obesity (reduction in hepatic fat by 20%, 30% decrease in fasting TGs, 26% reduction in apoB, 23% reduction in LDL-C, 40% reduction in fasting non-esterified fatty acids, and 11% decrease in fasting insulin). However, development of GW510516 was discontinued after observations in animal studies of its association with the rapid development of cancers in several organs.
The dual peroxisome proliferator-activated receptor-α/peroxisome proliferator-activated receptor-δ (PPARα/δ) agonist GFT505 has preferential α (EC50=6 nM) and secondary δ (EC50=47 nM) agonist activity. The lipid-modifying efficacy of GFT505 has been confirmed in both healthy subjects, as well as in patients with T2DM, combined abdominal obesity and mixed dyslipidemia, combined abdominal obesity and pre-diabetes, atherogenic dyslipidemia, and insulin resistance. These effects include reduction in TGs, non-HDL-C, and total cholesterol, LDL-C, and apoB; and increases in HDL-C. Preclinical studies in rodent models of NAFLD/NASH demonstrated that GFT505 treatment decreased hepatic steatosis, inflammation, and fibrosis, and decreased liver dysfunction markers; while in clinical studies GFT505 has been reported to decrease a range of liver dysfunction markers including ALT, alkaline phosphatase (ALP), and γ-glutamyl transferase (GGT). A 1-year liver biopsy-based Phase2b trial in NASH initially recruited patients for treatment with 80 mg/day of GFT505 or placebo, with an interim safety analysis at 6 months showing no safety issue that compromised the ongoing study; and a second recruitment phase has selected patients for treatment with 120 mg/day of GFT505 or placebo.
Obeticholic acid (OCA, 6α-ethylchenodeoxycholic acid), a semi-synthetic bile acid analog that is a highly potent farnesoid X receptor agonist, was studied in a Phase 2 study for NASH, the FLINT study, sponsored by the US National Institute of Diabetes and Digestive and Kidney Diseases. That study was halted early in January 2014, after about half of the 283 subjects had completed the study, when a planned interim analysis showed that the primary endpoint had been met. The treatment (OCA 25 mg/day for 72 weeks) resulted in a highly statistically significant improvement (p=0.0024 on an intention-to-treat basis, compared to placebo) in the primary histological endpoint, defined as a decrease in NAS of at least two points with no worsening of fibrosis.
Notwithstanding the initial benefits reported for GFT505 and OCA, there still remains a significant unmet clinical need for an effective and well-tolerated drug that can prevent or slow down the progression of NAFLD and NASH.
MBX-8025
MBX-8025 is the compound of the formula
MBX-8025 has the chemical name (R)-2-(4-((2-ethoxy-3-(4-(trifluoromethyl)phenoxy)propyl)thio)-2-methylphenoxy)acetic acid [IUPAC name as generated by CHEMDRAW ULTRA 12.0]. MBX-8025 and its synthesis, formulation, and use is disclosed in, for example, U.S. Pat. No. 7,301,050 (compound 15 in Table 1, Example M, claim 49), U.S. Pat. No. 7,635,718 (compound 15 in Table 1, Example M), and U.S. Pat. No. 8,106,095 (compound 15 in Table 1, Example M, claim 14). Lysine (L-lysine) salts of MBX-8025 and related compounds are disclosed in U.S. Pat. No. 7,709,682 (MBX-8025 L-lysine salt throughout the Examples, crystalline forms claimed).
MBX-8025 is an orally active, potent (2 nM) agonist of PPARδ, It is specific (>600-fold and >2500-fold compared with PPARα and PPARγ receptors). PPARδ activation stimulates fatty acid oxidation and utilization, improves plasma lipid and lipoprotein metabolism, glucose utilization, and mitochondrial respiration, and preserves stem cell homeostasis. According to U.S. Pat. No. 7,301,050, PPARδ agonists, such as MBX-8025, are suggested to treat PPARδ-mediated conditions, including “diabetes, cardiovascular diseases, Metabolic X syndrome, hypercholesterolemia, hypo-HDL-cholesterolemia, hyper-LDL-cholesterolemia, dyslipidemia, atherosclerosis, and obesity”, with dyslipidemia said to include hypertriglyceridemia and mixed hyperlipidemia.
A Phase 2 study of MBX-8025 L-lysine dihydrate salt in mixed dyslipidemia (6 groups, 30 subjects/group: once daily placebo, atorvastatin (ATV) 20 mg, or MBX-8025 L-lysine dihydrate salt at 50 or 100 mg (calculated as the free acid) capsules alone or combined with ATV 20 mg, for 8 weeks) has been reported by Bays et al., “MBX-8025, A Novel Peroxisome Proliferator Receptor-δ Agonist: Lipid and Other Metabolic Effects in Dyslipidemic Overweight Patients Treated with and without Atorvastatin”, J. Clin. Endocrin. Metab., 96(9), 2889-2897 (2011) and Choi et al., “Effects of the PPAR-6 agonist MBX-8025 on atherogenic dyslipidemia”, Atherosclerosis, 220, 470-476 (2012). Compared to placebo, MBX-8025 alone and in combination with atorvastatin significantly (P<0.05) reduced apoB100 by 20-38%, LDL by 18-43%, triglycerides by 26-30%, non-HDL-C by 18-41%, free fatty acids by 16-28%, and high-sensitivity C-reactive protein by 43-72%; it raised HDL-C by 1-12% and also reduced the number of patients with the metabolic syndrome and a preponderance of small LDL particles. While MBX-8025 at 100 mg/day reduced LDL-C by 22% over the total population treated, the percentage reduction in LDL-C increased to 35% in the tertile with the highest starting LDL-C levels (187-205 mg/dL), and trend analysis on individual patient data confirmed a positive correlation between percentage reduction in LDL-C and starting LDL-C level. MBX-8025 reduced LDL-S/VS by 40-48% compared with a 25% decrease with atorvastatin; and MBX-8025 increased LDL-L by 34-44% compared with a 30% decrease with atorvastatin. MBX-8025 significantly reduced alkaline phosphatase by 32-43%, compared to reductions of only 4% in the control group and 6% in the ATV group; and significantly reduced γ-glutamyl transpeptidase by 24-28%, compared to a reduction of only 3% in the control group and an increase of 2% in the ATV group. Thus MBX-8025 corrects all three lipid abnormalities in mixed dyslipidemia: lowers TGs and LDL and raises HDL, selectively depletes small dense LDL particles (92%), reduces cardiovascular inflammation, and improves other metabolic parameters: increases insulin sensitivity (lowers HOMA-IR, fasting plasma glucose, and insulin), lowers γ-glutamyl transpeptidase and alkaline phosphatase, significantly (>2-fold) reduces the percentage of subjects meeting the criteria for metabolic syndrome, and trends towards a decrease in waist circumference and increase in lean body mass. As explained in US Patent Application Publication No. 2010-0152295, MBX-8025 converts LDL particle size pattern I to pattern A; and from pattern B to pattern I or A, where LDL particle size pattern B is a predominant LDL particle size of less than 25.75 nm, pattern I is a predominant LDL particle size of from 25.75 nm to 26.34 nm, and pattern A is a predominant LDL particle size of greater than 26.34 nm, where the LDL particle size is measured by gradient-gel electrophoresis.
The disclosures of the documents referred to in this application are incorporated into this application by reference.